Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
335 PM MST Sat Jul 28 2018

.SYNOPSIS...Deeper moisture will allow for continued thunderstorm
chances through the weekend into much of next week. This will also
result in temperatures that are near average for late July/early
August.

&&

.DISCUSSION...The upper weather pattern this afternoon is defined by
an upper high centered over the Arizona/California border and an
inverted trough just west of the Baja Spur. The upper high center
continues to slowly wobble north/northwest in response to the trough
nudging it as it tracks NW. Northern extent of this trough is
becoming more in phase with a remnant MCV currently over the
southern Tohono Oodham Nation. This will result in an area of upper
diffluence across the southwestern portion of Arizona into this
evening which should help enhance thunderstorm activity. We have
seen some weak subsidence on the backside of the remnant MCV...
limiting thunderstorm intensity across Santa Cruz county. However,
we are now beginning to see signs this influence is waning with
storms developing across Wrn Cochise.

The 12Z KTWC upper sounding was quite moist and unstable with
precipitable water at 1.74 inches and unmodified MUCAPE of almost
2000. Combine this with the decent mid-level shear allowing storms
to organize, there should be plenty of ingredients around for storms
to become strong later this afternoon...especially to the S-W of
Tucson. The main impact of these storms will be the potential for
wet microbursts. Not only does this increase the potential for heavy
rain/flash flooding, but also strong organized thunderstorm outflows
which can result in blowing dust problems for the western deserts of
Arizona. Current LIS 0-200cm soil moisture satellite imagery depicts
plenty of dry soil remaining across the lower deserts as a source
for of dust. In any event, the majority of Hi-Res models still
suggesting there is the potential for an organized outflow making
their way toward Phoenix this evening. We have issued a Blowing Dust
Advisory for dust storm/Haboob formation through 8 pm MST.

Otherwise...the upper high will remain north our us through most of
the upcoming week. This will allow for an east to southeast pattern
to remain across SE Arizona. Therefore...we will continue with the
idea of higher than normal PoPs for much of the week along with near
normal temperatures.

&&

.AVIATION...Valid through 30/00Z
Scattered -TSRA/-SHRA with BKN cigs 8k-12k ft this afternoon and
evening. Brief MFR conditions are possible near the stronger storms.
Strong and erratic thunderstorm outflows are also possible,
especially to the SW thru NW of Tucson this afternoon and evening.
Blowing dust may reduce surface visibilities to below a mile at
times. Cloud coverage decreasing in the late evening and overnight.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Monsoon moisture will remain in place through the
end of next week with daily thunderstorm chances in the forecast.
Humidities will recover well each night and only drop to around 20-
30 percent each afternoon. Outside of thunderstorm induced gusts,
expect typical diurnal trends with speeds of 15 mph or less.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...Blowing Dust Advisory for
AZZ501>506-515 thru 8 PM MST.

&&

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Special Weather Statement
National Weather Service Tucson AZ
109 PM MST SAT JUL 28 2018

AZZ503-513-282045-
Dragoon/Mule/Huachuca and Santa Rita Mountains including
Bisbee/Canelo Hills/Madera Canyon-Upper Santa Cruz River and Altar
Valleys including Nogales-
109 PM MST SAT JUL 28 2018

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL SANTA CRUZ COUNTY
UNTIL 145 PM MST...

At 108 PM MST, Doppler radar was tracking a strong thunderstorm
near Nogales, moving southwest at 20 mph.

Dime size hail and wind gusts of 50 mph and blowing dust will be
possible with this storm.

Locations impacted include...
Nogales, Rio Rico Southeast, Rio Rico Southwest and Kino Springs.

LAT...LON 3133 11081 3133 11102 3146 11098 3144 11070
TIME...MOT...LOC 2008Z 057DEG 21KT 3134 11090

Special Weather Statement
National Weather Service Tucson AZ
355 PM MST SAT JUL 28 2018

AZZ504-507-513-282330-
Upper San Pedro River Valley including Sierra
Vista/Benson-Dragoon/Mule/Huachuca and Santa Rita Mountains including
Bisbee/Canelo Hills/Madera Canyon-Tucson Metro Area including
Tucson/Green Valley/Marana/Vail-
355 PM MST SAT JUL 28 2018

...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL PIMA COUNTY UNTIL
430 PM MST...

At 353 PM MST, Doppler radar was tracking a strong thunderstorm
between Vail and the Pima/Cochise county line, moving south at 5 mph.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Vail and Corona De Tucson.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall is also occurring with this storm, and may lead to
localized flooding and restricted visibility while driving. Do not
drive your vehicle through flooded roadways.

&&

LAT...LON 3205 11075 3204 11046 3190 11046 3189 11079
TIME...MOT...LOC 2253Z 008DEG 6KT 3199 11057